"I think... we're really going to see Hayley actually deal with the information that she is pregnant and that she is a young woman with a child, or a child about to come," Tonkin told IGN.

"It's nice to play a young adult finally. I've been playing 16 for a long time. And... having an issue like pregnancy with it - an unplanned pregnancy - is a very real topical issue, and it's nice to explore an issue like that within a supernatural world."

Daniel Gillies - who will also cross over into The Originals as Elijah - recently claimed that the show will be "darker" and "more adult" than The Vampire Diaries.

"[Joseph Morgan] and I are a bit older than the others," said Gillies. "I think that carries with it its own kind of energy and naturally you have to write for that."

The Originals will premiere on The CW on Tuesday, October 15, with the fifth season of The Vampire Diaries launching on Thursday, October 10.